The packaging of integrating circuit starts from the end of manufacturing of semiconductors. The object of the packaging is to increase the bearing and protection functions to protect the ICs from corrosion physically and chemically, to provide transferring paths of energy and signal distribution of the chips, to prevent the signals from delay so as not to affect the function of the system; and to provide heat dissipation path.
Referring to FIG. 1, in the process of IC packaging, the material is made of epoxy. The epoxy is melt to pass through a filling channel 91. The epoxy passes the filling channel 91 to the mold cavities 93 of the package mold 92 and the channel 94 between the mold cavities 93. After the package mold 92 is cooled, the resin will solidified so as to package the IC substrate and the semiconductors. However, in the packaging structure of the ICs, the pollution material (general carbide) accumulated on the surface of the mold cavities 93 of the package mold 92 and the corrosion on the surfaces of the mold cavities 93 will confine the lifetime of the package mold 92. Meanwhile, a long time is necessary to wash the package mold 92.
To improve the packing process, the surface process and design of the channels of the package mold 92 are important in the packaging of ICs. In one prior art, a protecting layer 95 is electric plated upon the surface of the package mold 92 with a thickness between 1 to 2 μm. The material of the protecting layer is hard chromium or polycrystal chromium nitride which is coated upon the surfaces of the mold cavities 93 so as to have preferred anti-corrosion ability and can be separated from the mold easily. However this prior art has the following disadvantages.
In the packaging process of the ICs, the resin will corrode the surfaces of the mold cavities 93 so that the corrosion is dramatic. In general, the Vickers hardness in electrical plating chromium to the protecting layer is about HV700. The corrosion will induce the viscosity on the surface of the mold cavities 93. This will reduce the lifetime of the package mold 92. Furthermore, a long time for clearing the package mold 92 is necessary.
Furthermore, in electrically plating chromium to the package mold 92, a high expense is necessary to clear the wasted water and gas in the electric plating process. Thereby a large operation space is necessary.
To coat nitride chromium to the package mold 92 by vacuum electric plating will have a Vickers hardness of HV1600 to 2000, but the protecting layer generally has a polycrystal cylindrical structure with worse anti-corrosion ability. Thereby the package mold 92 will be worn by the resin in packaging. Thereby it is difficult to separate from the mold.
As adhesive corrosion is formed on the surface of the package mold 92, the package mold 92 must be detached from a punching machine and is washed by strong acid or strong alkali which will corrode the surfaces of the mold cavities 93 of the package mold 92 with chromium or polycrystal nitride chromium so as to reduce the lifetime of the package mold 92.